Machine for grinding twist drills



April 23, 1929. s. c. PROBERT ET AL MACHINE FOR GRINDING TWIST DRILLS 4 sheets-Sheet Filed Oct. l0, 1924 -A RNEY S April 23, 1929. s. c. PROBERT ET AL.

MACHINE FOR GRINDING TWIST DRILLS Filed Oct. 10, 1924 4 Sheets-Sheet W .u A:

INVENTORS April 23, 1929. s. c. PROBERT ET AL MACHINE FOR GRINDING TWIST DRILLS 4 Sheets-Sheet Filed Oct. l0, 1924 f* HO lNvaNToRa L/P BY /D @Luana/16d ATTO April 23, 1929. s. ci PROBERT ET AL. 1,710,647

MACHINE FOR GRINDING TWIST DRILLS Filed G'C. lO, 1924 4 Sheets-Sheet 4 Patented Apr. 23, 1929.

UNITED STATES PATENTA OFFICE.

SIDNEY C. PROBERT AND ROBERT E. SPURR, 0F DETROIT, MICHIGAN, ASBIGNOBS, BY

MESNE ASSIGNMENTS; TO CHRYSLER WARE.

CGRPORATION, A CORPORATION 0l' DELA- MACHINE FOR GRINDING TWIST DBILLS.

Application filed October 10, 1924. Serial No. 742,770.

The present invent-ion relates to machines for grinding twist drills. y

It is highly important in grinding twist drills that the drill should be accurately ground according to certain specifications, in

order that the drill may cut with the proper` speed and accuracy. In the ordinary method of grinding 'a twist drill, the end faces only of the lips are ground to produce the cutting edges. Each cutting edge of a drill should be perfectly straight and parallel with the other cutting edge and the cutting edges should be accurately spaced 180 apart about the axis of the drill. These cutting edges also should be accurately located at the same distance from the axis of the drill. In order to produce these results, it is desirable not only to grind the end faces ofthe lips, but also to grind the inner faces of the lips.

The proper grinding of a twist drill by hand takes some time and requires considerable skill and care, so that the operation must be performed by a skilled operator.

The principal object of the present invention is to produce a new and improved machine for grinding twist drills upon which the inner faces of the lipsof such drills may be quickly and accurately ground, to locate the cutting edges of the drill in the proper relation to each other and to the axis of the drill.

With the above object in view7 the present invention relates particularly to mechanism for holding a twist drill and for controlling and guiding the same so as to present the inner faces of the lips of the drill to a rotary grinding wheel to grind accurately these faces of the lips. This mechanism is constructed and arranged so that the grinding operation may be quickly and accurately performed and so that the operation of the machine does not require any particular s ri ll.

In the present application', certain arts of the mechanism for holding a dril to present the end faces of the lips of the drill to the grindingr wheel and certain parts of the truing mechanism with which the ma- 0 chine is provided for truing up the grinding face of thegrinding disc, are illustrated. These mechanisms are not, however, herein described nor claimed, but form the subject tions, Serial Nos.

"8-8' of Figure 7 matter of applicants co-pending applica- 224,122 and 224,121, filed October 5, 1927.`

The various features of the invention will be 4clearly understood from the accompanying drawings illustrating the invention in its preferred form and the following detail description of the constructions therein shown. In the drawings- Fi re 1 is a view in front elevation of a grin ing machine embodying the invention;

Figure 2 is a view partly in plan and partly in section taken substantially on the line 2 2 of Figure 1;

`Figure 3 is a sectional view taken substantially on the line 3 3 of Figure 4 and illustrating one of the sets of drill-holding devices;

Figure 4 is a sectional view taken substantially on the line 4-4 of Figure 3;

Figure 5 is aI view in vertical section taken substantially on the line 5-5of Figure 1;

Figure 6 is a detail View in horizontal section taken substantially on the line 6-6 of Figure 1;

Figure 7 is a plan View of the mechanism for holding a drill in grinding the inner faces of the lips; Figure 8 is a View in verticalsection of the drill-holding devices illustrated in Figures 3 and 4, taken subtantially on the line Figures 9 and'lO are diagrammatic views illustrating the manner in which the drills are positioned vin the holding devices before grinding. Y

The machine embodying the present invention in the form illustrated in the drawings of this application is a double machine and comprises two rotary grinding discs indicated respectively at 2 and 4, secured to the opposite -endsof a shaft 6 mounted in bearings 8, formed on a bracket 10, secured to the upper end of a standard l2. Upon the shaft 6 is mounted a belt pulley 14 about which passes a suitable drivin belt (not shown); Each of the grinding isos is provided with a central recess extending inwardlyfrom the outer face as indicated in drill is moved relatively to the nism being associated with this disc for holding a drill to present the end faces of the lips to the peripheral portion of the grinding disc. A grinding disc 4 is provided for grinding the inner faces of the lips of drills.

In grinding the inner faces of the lips of a drill, the drill is presented to the grinding wheel 4 preferably in position to bring the inner face of a hp into tangential contact with the peripheral surface of the grinding wheel. During the grinding operation, the rinding wheel so that the grinding Wheel will make a grinding cut across the inner face of the lip inv a plane substantially parallel with thisl face. The drills are presented to the under portion of the periphery ofthe grinding disc 4, and are swung about an axis preferably substantially parallel with the plane of the disc to cause the grinding wheel to grind across the inner face of the lip. The drill is preferably located with its axis at an oblique angle to the axis of the rinding wheel to give a certain amount of ra e to the face of the 7lip, this rake being variable through suitable adjustments. The drill is clamped in an indexing chuck'sirnilar to the chuckI by which the drill is clamped for presentation to the grinding Wheel 2, and this chuck also is mounted to rotate about the axis of the drill. Also mechanism is provided for locating the chuck in either of two predetermined positions substantially 180o apart to locate either of the lips in position for grinding.

The chuck in which the drill is clampedl comprises a drill sleeve 78, a collet 80 surrounding the drill sleeve, a bushing 82 engaging one end of the collet, a barrel 84 in which the bushing is secured, and a sleeve 86 threaded into the barrel and engaging the opposite end of the collet. The barrel 84 is rotatably mounted in a supporting ring 88, and is provided With bushings located 180 apart to receive a locking pin 90 upon which is pivoted an operating lever 92. 'The parts of the chuck just described have substantially the same construction, arrangement and mode of operation as the parts of the chuck for holding a drill in position for grinding the end faces of the lips, shown and described in applicants co-pending application, Serial No. 224,122.

When a drill is insertedin a chuck, the barrel 84 is locked in position by the engagement of the locking pin 90 in one of the bushings in said barrel. In grinding the inner fr ces of the lips of a drill, the drill is inserted inthe drill sleeve 78 which has been allowed to expand by turning the sleeve 86v to receive the drill and the drill ispositioned longitudinally so that the chuck Will grip the drill at the desired distance from the point. When the drill has been located in the locking pin snaps the supporting rin the proper longitudinal and rotary position in the drill sleeve, the sleeve 86 is rotated to clamp the drill in position in the chuck. When the grinding of the inner face of one lip is completed, the locking pin 90 is disengaged from the bushing in the barrel 84 and the barrel is turned through 180o until into the other bushing. This will locate the other lip of the drill in position to be ground.

`To enable the rake at which the inner face of the lip of the drill is ground to be varied,

0 88 is pivoted upon trunnions 94 between die arms of a yoke 96 secured to a supporting arm 98. This construction enables thel drill to be tilted at different angles with relation to the plane of the grinding wheel. The ring 88-is held in adjusted position With relation to the yoke 96 by means of bolts 100 threaded into the ring and engaging in slots 97 in the arms of the yke.

The supporting arm 98 is pivoted by a stud 102 to an arm 104 to swing preferably upon an axis substantially parallel with the planeof the grinding disc to carry a drill past aid disc.

To enable a drill in justed vertically into contact with the lower margin of the grinding Wheel the arm 104 is mounted for vertical adjustment. To this end the arm 104 is secured to the upper end of a guide stud 106 (see Fig. 5) mounted to slide vertically in a correspondingly shaped guideway in a bracket 108 secured to the frame of the niachine and the stud is held from turning in the bracket by a suitable key. The guide vstud 106 is hollow and Within the same is engaged a hollow stud 110, lthe lower end of which is seated in a collar 112 secured to the bracket 108. Within the studs 106 and 110 is rotatably mounted a shaft 114, the lower end of which is threaded and engages corthe chuck to be ad- `responding screw threads formed on the interior of the stud 110. The shaft 114 is provided with an outwardly extending flange 116 which supports a bushing 118 secured to the arm 104. Thus the rotation of the shaft 114 in opposite directions will raise and lower the arm 104. The shaft is arranged to be rotated by mechanism comprisin a spiral gear 120 secured to the u ei en 'of the shaft and a spiral gear 122 (p ig. 2) secured to a shaft 124mounted in bearings in a'casing secured to the arm 104. A hand Wheel 126 is secured to theforward end of the shaft 124 to enable the shaft to be manually rotated. The stud 106 and the arm 104 are 'held in adjusted position by means comprising a 'clamping sleeve/ 128 mounted to slide longitudinally in a bore in the bracket 108 and arranged to engage the stud at its inner end. The clamping sleeve is actuated to clamp the stud by means of a proper position for bolt 130 passing through the sleeve and threaded into a nut 131 secured to the bracket. (See Fig. 6.)

In order to locate the end, of the drill in the proper position transversely of the grinding disc the bracket 108 is mounted to slide on a horizontal stud 132 and is adjusted I longitudinally of the stud by means ofl a Cil -is substantially rotatable pinion 134 mounted in the bracket and meshing with teeth on the stud. The pinion is .secured to a shaft 136, the outer! end of which is shaped to receive a crank handle for turning the same. The bracket 108 is clamped in position on the stud 132 by mechanism which comprises the clamping sleeve 138 mounted to slide inthe bracket 108 and arranged to engage the stud 132 and a shaft 140 passing through the sleeve and threaded into a nut mounted iii the bracket for actuating the sleeve. The outer end of the shaft 140 is also shaped to receive a crank handle or other suitable tool.

In order to prevent the bracket 108 from turning on the stud 1.32 the bracket is provided at its lower end with a projecting rib engaging in a guideway formed 1n an arm 146 projecting from the. frame of the machine. Q

Before placing a drill lin the drill-holding chuck the arm 98 'is swung forwardly from the position shown in Figure 7, so that the drill will not contact with the grinding disc when inserted in the chuck, dand the barrel 84 is located in position with the locking pin engaging in one of the bushings in the barrel. The drill is inserted in the drill. sleeve 78 and turned until the inner face of the lip occupying the lower position tangential to the periphery of the grinding disc. The drill is then clamped in the chuck by turning the clamping sleeve 86 after which the arm 104 is adjusted vertically to bring the inner face of the lip vof the drill into position for grinding contact with the periphery of the grinding Wheel. The arm 98 is thenv swung rearwardly about the stud 102 to carry the inner face of the lower lip of the drill across the periphery of the grinding wheel. To enable the inner face of the lip to be ground to be located accurately in the proper angular position the machine is provided with a lip-locating gage block 150 secured to the upper end Lof a spindle 152 mounted to rotate in a'supporting arm 154. The arm 154 is pivoted at 156 on an arm 158 which is secured to a shaft 160 mounted to slide longitudinally in a bearing in the arm 98. The

shaft 160 is secured from longitudinal movement and also from turning 'in its bearing in the arm 98 by means of a screw threaded` pin 162 threaded into the arm 98, the inner end of which engages in a longitudinal groove 164 lin the shaft 160 and is arranged to be forced against the bottom of the groove.

The arm 154 is mounted to swin so that the gage block will en around the pivot 156 to carry the gagel b ock into and out of operating osition. The gage block may be adjuste screwing the pin 162 and adjustin the shaft 160 longitudinally. The gage' lock 150 preferably is in the form of a rectangular prism, the upper surface of `which is substantially tangential to the periphery of the grinding wheel. In positioning a drill by means of the gage block, with the arm 98 swung back out of grinding position, a drill vis inserted in the drill sleeve and is located longitudinally in the sleeve by the operator age the point of the drill. The gage block 1s then swung back into engagement with `the point of the drill, as shown in Figure 7, and the drill is rotated about its axis until the inner face of the lip occupying the` lower position is in alignment with the upper face of the ga e block. This is determined by the eye. Tle drill is then clamped in position in the chuck and the gage block is swung back out of the way. The drill carrier may, of course, be adjusted vertically or transversely of the grinding disc to locatethe inner face of the lip properly with relation to the grinding wheel before starting the grinding operation. After the drill ris properly located the grinding operation is performed by swinging the arm 98 to carry the point of the drill past the grinding wheel. After one grinding cut has been taken the drill carrier may be adjusted vertically to a slight degree to take,a slightly deeper `cut if desired.

l/Vhen Athe face of one lip is ground the barrel 84 is unlocked by releasing the locking pin 90 4and is turned through 180o until the locking pinengages the opening in the opposite bushing. This will locatev the other lip of the drill in position for grinding and the grinding operation is performed in the same manner as before.

The machine isprovided with mechanism for supporting twov truing tools, one for each vertically by ungrinding disc, for truing up the grinding surfaces of the discs.

Figures 9 and 10 illustrate the manner in screwing and removing the actuating sleeve` 86. Thus the collet and drill sleeve for one l quickly and easily.

Upon the present machine drills of various sizes may be ground with a high devgree offaccuracy and no rparticular skill is required in operating themachine. Upon the present machine the drill grinding operation may be performed by an unskilled operator and the time ordinarily required in the grinding of twist drills is greatly reduced. Thus a large part of the cost of inaintaing such drills in sharpened condition in manufacturing plants will be saved by the use of this machine.

In the present machine the drill is held by its finished outside surface in each grinding operation and is indexed about the true 'center or axis of this surface. Thus the lips ofthe drill are ground accurately in predetermined relation to the outside surface of the drill.

Itis to be understood that the invention is not limited to the particular construction and arrangement of parts of the illustrated embodiment of the invention but that the invention may be embodied in other forms wit-hin the scope of the claims.

Having thus described our invention, We'

1. A grinding machine having in combination a rotarygrinding wheel, means for holding a twist drill with its axis oblique to the plane of the grinding wheel in positiony to present the inner face of a lip to the grinding Wheel at an angleto give the desired rake, and mechanism for supporting said holding means for movement to carry the inner face of the lip past the grinding wheel in the general direction of the edge of the lip.

9J. A grinding machine having in combination a rotary grinding wheel, means for holding a twist drill with its axis oblique to the plane of 4the grinding wheel in position to present the inner face of a lip to the wheel in tangential relation to the peripheral surface nf the wheel with the cutting edge of the lip extending in the general direction of ,the plane of the Wheel, and mechanism for supporting saidholdilng means for movement to carry the inner face of the lip past the grinding wheel in the general direction of the edge of the lip.

3. A grinding machine having in combination a rotary grinding wheel,means for Aholding a twist drill with its axis oblique to the plane of the grinding wheel in position to present the inner face ot a lip to the grinding wheel at an angle to give the desired rake, mechanism .for supporting said holdin means for movement to carry the inner ace of the lip past the grinding wheel in the general direction of the edge of the lip, and mechanism for locating said holding means angularly about the axis of the drill in positions 180 apart to position the inner face `of each lip with relation to the grinding wheel. 1

4. 'A grinding machine having in combination a rotary grindin wheel7 a drill-carrying arm, means on said arm for holding a twist drill with its axis oblique to the plane of the grinding wheel in position to present the inner face of a'lip to the grinding wheel at an angle to give the desired rake, and means for pivotally supporting said arm to swing on an axis offset from the axis of the drill and transverse thereto to carry the inner face of the lip past the grinding wheel inthe general direction of the edge of the lip by the movement of said arm.

5. A drill grinding machine having in combination a grinding wheel, a swinging arm for supporting the drill in position to present the same to the grinding wheel, a pivotal ar'm for supporting the pivot of said first arm, and means for adjusting the latter arm to adjust laterally the axis of the first arm.

(L A drill grinding machine having in combination a grinding wheel, a swinging arm pivoted on an axis substantially parallel with the grinding wheel, means on said arm for holding a twist drill with its axis oblique to the plane of the grinding wheel in position to present the inner face of a lip to the grinding wheel at an angle to give the desired rake, an arm for'supporting the pivot of said first arm adjustably pivoted on an axis substantially parallel with the axis -ot the first arm, and means for adjusting the latter arm to adjust the pivot of the first arm laterally.

7. A drill grinding machine having in combination a grinding wheel, a drill-carrying arm arranged to swing to carry the inner face of a lip of a twist drill across the periphery of the grinding wheel in a gen eral direction parallel with the plane of the grinding wheel and also in the general direction of the cutting edge of the lip of the drill, and means for pivotally supporting said arm.

s. A drin. grinding machine having irri combination a grinding wheel, a drill-carrying arm arranged to swing to carry the inner face of alip of a twist drill across the periphery of the grinding wheel in a general direction parallel with the plane of the grinding wheel andalso in the general direction of the cutting edge of. the lip of the' drill, and means for pivotally supporting said armbarranged for adjustment to adjust the pivot of the arm in a direction substantially parallel with the plane of the wheel. 9. A drill grinding machine having in combination a grinding wheel, a drill-carrying arm arranged to swing to carry the inner face of a lip of a twist drill across the periphery of the grinding wheel in a general direction parallel with the plane of the grinding wheel and also in the generaldirection of the cutting edge of the lip of the drilland means for pivotally supporting the arm arranged for adjustment to adjust the pivot of the arm in a direction transverse to the plane of the wheel.

10. A drill grinding machine having in combination a grinding wheel, a drill-carrying arm arranged to swing to carry the inner face of a lip of a twist drillv across the periphery of the-grinding wheel in a general direction parallel with the plane of` the grinding wheel and also in the general direction of the cutting edge of the lip of the drill, and means for pivotally supporting the arm arranged for adjustment to adjust the pivot of the arm in directions transverse to and substantially parallel with the plane of the wheel. i

11. A grinding machine having in combination a rotary grinding wheel, means for holding a twist drill with its axis oblique to the plane of the grinding wheel in position to present the inner face of a lip to the grinding wheel atV an -angle to give the desired rake, mechanism for supporting said holdin" means for movement to carry the inner face of the lip past the 'rinding wheel infthe general direction of the edge of the lip, and means for adjusting the drill holding means to adjust said face of the lip t0- ward and from the axis of the grinding Wheel. l

12.` A grinding machine having in combination a rotary grinding wheel, means for holding a twist drill with its axis oblique to the plane of the grinding wheel in position to present the inner face of a lip .to the grindin Wheel at an angle to give the desired ra e, mechanism for supporting said holding means for movement to carry the inner face vof the lip past the grinding wheel in the general direction of the edge of the lip, and mechanism by which the relation of the axis of the drill to the grinding wheel may be adjusted to adjust'the rake at which the inner face ofthe lip is ground.

13. A grinding machine for grinding the inner face of the cutting lip of a twist drill,

ypresented thereto.

having in combination a rotary grinding wheel, means for holding a. twist drill with its axis inclined to the wheel in one plane to locate the cutting edge of the lip in a position substantially parallel with the plane of the wheel and tangent to the periphery of the wheel, and in another plane to give the desired rake to said face of the drill when ground, the grinding wheel and holder being relatively movable to carry the inner face of the lip across the adjacent face of the grinding Wheel in Contact therewith in a direction substantially parallel to the plane of rotation of the grinding wheel and.

lengthwise of said cutting edge.

14. A grinding machine for grinding the inner face of the cutting lip of a twist drill, having in combination a rotary grinding wheel, means for holding a twist drill with its axis inclined to the wheel in one plane to locate the cutting edge of the lip ina position substantially parallel with the plane of the wheel and tangent to the periphery of the wheel, and in another' plane to give the desired rake to said face of the drill when ground, the drill holding means being pivoted to carry the inner face of the li past the grinding wheel in contact therewitii in the direction of a line tangent to the periphery of the wheel and lengthwise of said cutting edge.

15. A drill grinding machine, having in combination a grindmg disc, means for holding a drill in position for grinding the inner face of a lip of the drill and a gage for' locating the inner face of a lip 1n a position substantiall ripheral surface ol" the grinding wheel when 16. A drill grinding machine, having in combination a grinding disc, means for holding a twist drill in position to be ground on the wheel, and a gage having a face occupying a predetermined position with relation to the discv and arranged so that the drill will be properly `located angularly with relation to the disc by locating the inner face of a lip of the drill flush withsaid face of the gage.

this 7 day Signed 4at Detroit, Michigan, of 0ctober, 1924.

f SIDNEY C. PROBERT.

ROBERT E. SPURR.

tangenitial to the pe 

